Rail vehicle

ABSTRACT

The invention relates to a rail vehicle comprising a chassis provided with individual wheels which are respectively mounted on axle carriers in such a way that they can pivot in the horizontal direction about a vertical steering axis. Said rail vehicle also comprises a steering actuator associated with each wheel, for adjusting a pre-determined steering angle about the vertical steering axis, the wheels ( 1 ) of the axles being respectively mounted in such a way that they can be pivoted in the vertical direction about a horizontal camber axis (S) and can be acted upon by means of a camber actuator ( 7 ) in order to adjust a pre-determined camber angle (α S ).

The invention relates to a rail vehicle comprising a chassis providedwith individual wheels which are respectively mounted on axle carriersin such a way that they can pivot in the horizontal direction about avertical steering axis. Said rail vehicle also comprises a steeringactuator associated with each wheel, for adjusting a pre-determinedsteering angle about the vertical steering axis.

DE 40 40 303 A1 discloses a rail vehicle with a chassis, of whichindividual wheels are mounted on an axle carrier, which is mounted forpivoting in the horizontal direction about a vertical steering axis. Thewheels cooperate with a steering actuator, so that the wheels duringtravel can be adjusted to a predetermined steering angle. The railvehicle includes an independent-wheel running gear and can be activelysteered by actuation of the steering actuator on the wheels.

The disadvantage of this known rail vehicle is that the track guidanceand track steering during negotiation of curves or, as the case may be,passive switch plates, is not reliably taken into consideration and inunfavorable circumstances could lead to derailing of the rail vehicles.

It is thus the task of the present invention to further develop a railvehicle of this type such that a safe, reliable and robust rail guidancethereof is ensured.

In combination with the pre-characterizing portion of claim 1, thesolution of this task is solved thereby, that the wheels of the axle arerespectively mounted in such a way that they can be pivoted in thevertical direction about a horizontal camber axis and can be actuated bymeans of a camber actuator for adjusting the predetermined camber angle.

The particular advantage of the invention is comprised therein, that areliable and robust rail guidance and rail steering is made possible,which is independent of the coefficient of friction of awheel-rail-contact point. If the coefficient of friction drops due toweather conditions, such as ice or foliage on the rails, then the railvehicle speed need not be reduced in the curve.

It is the basic idea of the invention to decouple the dependence of therail guidance or piloting friction. In accordance with the inventionthis occurs thereby, that the camber of the wheels is changed or, as thecase may be, that this is tilted sideways to the vehicle longitudinalaxis. Since the rails have a hemispherical cross-sectional profile, thewheels can support themselves thereupon.

In accordance with a preferred embodiment of the invention, a camberactuator is controlled in such a manner, that the wheel is oriented in acentral position or camber position, in that exclusively normal forcesare transmitted in the wheel contact point. The wheel is thus tiltedsideways in such a manner that no frictional forces exist in thetransverse direction. Thereby transverse forces occurring duringnegotiation of a curve can be completely supported via the sidewaysforces on the contoured sides. The friction at the wheel-to-rail-contactpoint can be reduced. An absence of slippage in the transverse directioncan be ensured.

According to a further development of the invention the wheel is mountedvia a four-bar linkage to the chassis. Advantageously thereby undesiredmovements of the chassis can be avoided. Thereby the space between theinstantaneous center of rotation and the wheel-to-rail contact point canbe kept small.

According to a further development of the invention the wheel is mountedto the chassis via a king-pin steering.

According to a particular embodiment of the invention one fixed camberaxis per wheel can be provided, which is oriented perpendicular to thesteering axis and parallel to the vehicle longitudinal direction.

According to a second embodiment of the invention the camber axis can bevariable depending on the camber angle. Therein the wheel is coupled tothe axle carrier via a cross linkage or control arm or wishbone.

Further advantages of the invention can be seen from the dependentclaims.

Illustrative embodiments of the invention are explained in the followingon the basis of the figures.

There is shown:

FIG. 1 a: a schematic vertical section through a chassis of a railvehicle according to a first embodiment,

FIG. 1 b: a horizontal section through the chassis according to thefirst embodiment,

FIG. 2 a: a schematic vertical section through a chassis according to asecond embodiment,

FIG. 2 b: a horizontal section through the chassis of the secondembodiment, and

FIG. 3: a schematic representation of a camber position of the wheel.

A rail vehicle is moved along the rails 4 by a not shown drive and/orbraking unit in the vehicle in the longitudinal direction (transverse tothe image plane according to FIG. 1 a) with rolling of the wheels 1.

The wheels 1 are a component of a chassis 2, which is provided in anot-shown rail carriage body.

The chassis 2 includes elongate axle carriers 3, upon the opposite endareas of which the wheels 1 are respectively individually mounted.

For adjusting to a predetermined steering angle α_(L) about a verticalsteering axis V a steering actuator 5 is provided. The steering actuator5 is mounted between an arm 6 and the not-shown wheel hub provided inthe wheel 1. The vertical steering axis V extends in a central radialplane M_(R) of the wheel 1.

The steering actuator 5 is controlled via a not shown control unit insuch a manner, that the wheel 1 is adjusted according to such a steeringangle α_(L), that the wheels 1 are guided along one of the curve radiusr set by the rails 4.

For setting a predetermined angle α_(F) of the wheel 1 a camber actuator7 is provided, which is provided between the axle arm 8 and the axlecarrier 3.

According to a first embodiment of the invention as shown in FIGS. 1 aand 1 b the wheel 1 is pivotable about a fixed horizontal camber axis S,which runs at a vertical height, which is set below a horizontal axleplane of the wheel 1. The camber actuator 7 engages above the horizontalaxial plane of the wheel 1.

The camber axis S is provided perpendicular to the vertical longitudinalaxis V and in the vehicle longitudinal direction. The horizontal camberaxis S and the vertical longitudinal axis V intersect in the centralradial plane M_(R) of the wheel 1.

The camber actuator 7 is controlled via a not shown control unit in sucha manner, that the wheel 1 is pivoted, depending upon the longitudinalangle α_(L), in such a way about the camber angle α_(S) sideways of thecentral position in a camber position, so that at the wheel contactpoint P exclusively normal forces F_(N) are transmitted. As can be seenfrom the camber position of the wheel 1 shown in FIG. 3, the camberangle α_(S) of the wheel 1 corresponds to the angle α_(F), which islocked in or implemented on the one hand by the vertical force F_(V) andon the other hand by the force F_(R) resulting from the combination ofthe vertical force F_(V) and the transverse force F_(Q).

The camber actuator 7 can be controlled during negotiating of a curve insuch a manner, that the camber angle α_(S) is computed from therelationship

${{\tan \mspace{14mu} \alpha_{S}} = \frac{v^{2}}{rg}},$

-   -   wherein v is the vehicle speed, r is the steering radius and g        the gravitational acceleration.

According to a second embodiment of the invention as shown in FIGS. 2 aand 2 b the camber actuator 7 is connected via a twin control arm orsuspension arm 9 of a control arm or suspension arm unit 10 with thewheel 1 in an articulated linkage. The same components or, as the casemay be, component functions are provided with the same referencenumbers.

The control arm unit 10 is comprised of two twin control arms 9, 9′,which extend from a common axle arm 11 on both sides of the centralradial plane M_(R) of the wheel 1. By adjusting the wheel 1 about thecamber angle α_(S) a tilting of the wheel 1 about a variable camber axisS occurs. This is preferably situated below a horizontal axial plane ofthe wheel 1. The twin control arms 9 or, as the case may be, 9′ exhibitrespectively parallel control arm axis 12.

The steering actuator 5 is mounted between a steering rod 13 and the notshown wheel hub provided in the wheel 1.

The wheel 1 can be mounted in the chassis 2 via a four-bar linkage.Preferably the wheel 1 is mounted in the chassis 2 via a king-pinsteering.

The vertical steering axis V preferably runs in the central radial planeM_(R) of the wheel 1.

1. A rail vehicle with a chassis provided with individual wheels whichare respectively mounted on axle carriers, which are mounted in such away that they can pivot in the horizontal direction about a verticalsteering axis, and a steering actuator associated with each respectivewheel for adjusting a predetermined steering angle about the verticalsteering axis, thereby characterized, that the wheels (1) of the axlerespectively are mounted pivotable in the vertical direction about ahorizontal camber axis (S) and by means of a camber actuator (7)actuatable for adjusting a predetermined camber angle (α_(S)).
 2. Therail vehicle according to claim 1, wherein the camber actuator (7) iscoupled with the wheel (1) and wherein the camber actuator (7) iscontrolled in such a manner, that the wheel (1) is oriented in acentered or a chamfered position, in which exclusively normal forces aretransmitted at the wheel contact point (P).
 3. The rail vehicleaccording to claim 1, wherein the camber actuator (7) is controlled insuch a manner, that the camber angle (α_(S)) is the same as an acuteangle (α_(F)), which is comprised of the sum of a vertical force (F_(V))running in the vertical direction and a transverse force (F_(Q)) runningin the horizontal direction and extends or arranges on the one hand theresulting force (F_(R)) acting upon the wheel contact point (P) of therail and on the other hand on the vertical force (F_(V)).
 4. The railvehicle according to claim 1, wherein the camber actuator (7) iscontrolled in such a manner, that the camber angle (α_(S)) of the wheel1 is adjusted according to the relationship${{\tan \mspace{14mu} \alpha_{S}} = \frac{v^{2}}{\underset{\_}{rg}}},$wherein v is the speed of the rail vehicle, r the steering radiusaccording to the curve being negotiated by the rail vehicle, and g isgravitational acceleration.
 5. The rail vehicle according to claim 1,wherein the wheel (1) is mounted on the chassis (2) via a four-barlinkage.
 6. The rail vehicle according to claim 1, wherein the wheel (1)is mounted via a king pin steering in the chassis (2).
 7. The railvehicle according to claim 1, wherein the control unit acts on a camberactuator (7) engaging the wheel (1) via an articulated linkage, in sucha manner, that the wheel (1), depending upon the steering angle (α_(L)),is pivoted out of a central position (M) by camber angle (α_(S)) in thesupport axis (S).
 8. The rail vehicle according to claim 1, wherein thecamber actuator (7) is linked directly to the wheel (1), in such amanner, that the wheel (1) is pivotable about a fixed camber axis (S),which runs approximately the height of one of the areas of the wheel (1)close to the rail.
 9. The rail vehicle according to claim 1, wherein thecamber actuator (7) is linked to the wheel (1) via a twin control arm(9, 9′) of a control arm unit, wherein the twin control arms (9, 9′) ina central or normal position of the camber actuator (7) run symmetric toa central radial plane (R_(M)).
 10. The rail vehicle according to claim1, wherein the vertical steering axis (V) extends or runs in the centralradial plane (M_(R)) of the wheel (1).